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The weekly Lost Knowledge column explores the possible technology of the future in the forgotten ideas of the past (and those slightly off to the side). Each Tuesday, we look at retro-tech, "lost" technology, and the make-do, improvised "street tech" of village artisans and tradespeople from around the globe. "Lost Knowledge" is also the theme of MAKE Volume 17 (due on newsstands March 10, 2009)

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"They say the neon lights are bright on Broadway," but those lights are fading, fast. If neon was the high-tech lighting of the 20th century, the LED is the tech of the early 21st. But while neon is not likely to have much of a future in widespread application, it will likely always have retro-cool appeal, and a place of pride in the repertoire of the glass blowers arts.

So what exactly is neon light? The concept of illuminating a gas with a discharge dates back even before the discovery of electricity, when it was observed that mercury would glow in a barometric tube when shaken. In the mid-1800s, with the invention of electrical generators, scientists began experimenting with applying voltage discharges to various gases inside of sealed glass tubes, called geissler tubes, after their inventor, German physicist Heinrich Geissler.

Color drawing of Geissler tubes from an 1869 French natural philosophy book, showing some of the many fanciful shapes. Caption: "ELECTRIC DISCHARGE IN RAREFIED GASSES. [via Wikipedia] Here's a scan from "How to Make an Experimental Geissler Tube," Popular Science, February 1919, which you can view via Google Books.

 

In 1902, French engineer and chemist Georges Claude was the first person to apply an electrical discharge to a sealed tube of neon gas, and the neon light was born. Claude applied for a patent on the neon lamp in 1915. The first neon sign in the US, installed in 1923, was created by Claude's company, Claude Neon, and was for a Packard dealership in Los Angeles.

 

U.S. Patent 1,125,476. Filed by Georges Claude, Jan. 19th, 1915.

 

Making a Neon Sign (excerpt from The History of Neon Signs on About.com)

Hollow glass tubes used to make neon lamps come in 4, 5 and 8 ft lengths. To shape the tubes, the glass is heated by lit gas and forced air. Several compositions of glass are used depending on the country and supplier. What is called 'Soft' glass has compositions including lead glass, soda-lime glass, and barium glass. "Hard" glass in the borosilicate family is also used. Depending on the glass composition, the working range of glass is from 1600' F to over 2200'F. The temperature of the air-gas flame depending on the fuel and ratio, is approximately 3000'F using propane gas.

The tubes are scored (partial cut) while cold with a file and then snapped apart while hot. Then the artisan creates the angle and curve combinations. When the tubing is finished, the tube most be processed. This process varies depending on country; the procedure is called "bombarding" in the US. The tube is partial evacuated of air. Next, it is short circuited with high voltage current until the tube reaches a temperature of 550 F. Then the tube is evacuated again until it reaches a vacuum of 10-3 torr. Argon or neon is back filled to a specific pressure depending on the diameter of the tube and sealed off. In the case of an argon-filled tube, additional steps are taken for the injection of mercury; typically, 10-40ul depending on tube length and climate it is to operate in.

Red is the color neon gas produces, neon gas glows with its characteristic red light even at atmospheric pressure. There are now more than 150 colors possible; almost every color other than red is produced using argon, mercury and phosphor. Neon tubes actually refer to all positive-column discharge lamps, regardless of the gas filling. The colors in order of discovery were blue (Mercury), white (Co2), gold (Helium), red (Neon), and then different colors from phosphor-coated tubes. The mercury spectrum is rich in ultraviolet light which in turn excites a phosphor coating on the inside of the tube to glow. Phosphors are available in most any pastel colors.

 

A Neon Timeline from New York Magazine (A few scientists run an electric current through a sealed glass tube, and the next thing you know, the Pepsi-Cola sign is lighting up the East River. How we got there.)

 

New Orleans neon artist Eric Ehlenberger has some technical info (along with pictures and video) on his website detailing how he goes about creating his neon sculptures (scroll down to the "Technical Information section"). Here's an excerpt from his section on Transformers:

Neon tubes light up when the gas within the tube is "excited" by being bombarded with high-energy electrons. The collision between electrons results in light: the same phenomenon as lightning in the sky. The transformer functions to "transform" either 110 Volt 60Hz (AC current from standard wall outlets) or 12 Volt DC (battery-type current) to a form which has higher energy.

There are 2 types of transformers that are used in the neon industry. The old-style transformer characterized by "beer-sign" transformers which are bulky and very heavy - they put out high voltage/low frequency electricity to light the tube. They often "buzz" when on, causing interference on television or telephones and have no safety features. I rarely use them in my work.

The other type of transformer is electronic in nature and puts out high frequency electricity (20,000 Hz and above) to light up the neon. This is the type I use in almost all of my work. They are lightweight, compact and quiet in operation. They should not interfere with television or telephone reception as the old-style may. In addition, they have safety features which allow them to shut off if overloaded or if they detect a faulty tube.

The transformers run warm when on but should not be too hot to touch. If for some reason this is detected, turn the piece off (unplug). If the tubes flicker on and off, this is usually a sign of a faulty transformer and it should be unplugged. When necessary, exchanging a faulty transformer is a simple process.

The transformers have manufacturer's warranties of 1-2 years. The life span of these transformers is not really known, having been on the market for only 10-15 years or less. Many transformers of this style have been in use by the artist now for 10+ years without problems.

 

Shawna Peterson of Peterson Neon is a neon glassblower who's presented her work at Maker Faire. Here she's using a six-head cross fire burner for glass welding and bending.

From "Lady Bends the Tubes," by Arwen O'Reilly, MAKE Volume 10, Page 120:

Shawna Peterson was in the middle of completing a degree in psychology when she landed a part-time job "babysitting the store" at a neon shop to help pay her way through school. After two years, she started an old-fashioned apprenticeship with the tube bender after work, mastering each step before she was allowed to proceed to the next. "Even after five years, you're still a journeyman," she says matter-of-factly. 20 years later, she's a master glass bender who divides her time between creating commercial neon for businesses, teaching neon bending at her workshop in Emeryville, Calif., and making neon artwork, whether commissioned or her own. Does her background studying cognition help? "Bending a neon pattern is like working a mental puzzle, every time," she says. "You need to plan it out, carefully and creatively."

Her workshop is packed with her own work and the tools, both high-tech and humble, of her trade. She admits that her favorite tool is a charred wood block that she's been using for the last 15 years to cool freshly bent glass, but her cross-fires for bending the glass tubing are pretty impressive as well. While glass-bending technology hasn't changed much since the early days, she's the possessor of a modern, greaseless o-ring vacuum manifold for emptying oxygen and other impurities from the bent tubes and then pumping in neon and argon. Once the tubes are sealed and wired to the transformer, it's time to let there be light. After all, "there's nothing more satisfying than building something from scratch and then lighting it up."

Read the Web exclusive interview with Shawna Peterson here.

Cala Foods commercial signage by Shawna Peterson.

 

Light Figure Fragment, by Craig A. Kraft (Bonded Copper and Neon 4.5' x 4' x 3/4')

Note: The Nixie Tube, a cold-cathode tube technology, popular in the 50s - 70s for displaying numerals and other data, is also a type of neon lamp. We will cover them in a future Lost Knowledge column.

[Thanks to reader Mlg in the Comments for suggesting this column topic.]

 

More:

• Lost Knowledge: Reanimating Dead Media
• Lost Knowledge: Manual typewriters